Automated generation of control interface to controlled element of telecommunications network

ABSTRACT

To facilitate the creation of an interface between a network control layer and controlled elements in the network, on insertion of a new element to be controlled an intelligent interface creates a compatibility listing between the network control layer and the element manager, the intelligent interface carries out steps of “look around”, “try and see”, “follow instructions” and “structured questioning”. Each of these steps, in association with a dictionary of “comparable information” results in data being added to a knowledge frame which defines the element and its message format handling requirements.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a network interface and moreparticularly to such an interface for use in translation of codedelectrical signals. The invention also relates to methods ofconstructing such an interface.

2. Related Art

Modern communications networks often comprise a number of layers each ofwhich may include “intelligence”. The layers have a hierarchicalstructure with higher layers making use of functions provided by lowerlayers to complete assigned tasks. Accordingly an element (or function)in one layer may provide service to an element or function in the layerabove and may demand a service from an element or function in the layerbelow (if any). Thus it is necessary for elements and functions to beable to pass messages between each other. Clearly there has to be someknown structure for the messages sent between the layers this structurebeing known as a message protocol.

Where a complete network is supplied by a single manufacturer, themessage protocols are specified by that manufacturer and provided thenetwork does not need to communicate with any other network there is noproblem.

However for larger networks, for example for public switched telephonynetworks (PSTN), it would be unacceptable if the PSTN operator were tobe tied to a single manufacturer. Consequently each layer of the PSTNmay contain elements from several suppliers, some of which will performcommon functions but with a differing message protocol.

Hitherto it has been common practice for the network operator to specifyto manufacturers the message protocol to be used by element managers ofelements to be incorporated into particular network layers. However,this results in increased costs since each network may require bespokeelement manager software to be provided.

An alternative is for the network operator to accept the manufacturersmessage protocol and to provide bespoke software in the controllinglayer. Such arrangements are equally expensive and may lead toinflexibility in the network since it would not be practical to replacean element from one manufacturer with a corresponding element (having adifferent message protocol) from another manufacturer. The presentinvention seeks to alleviate the difficulties arising from messageprotocol incompatibility.

SUMMARY OF THE INVENTION

According to the present invention there is provided a method ofconstructing an interface between a control layer and a controlledelement of the kind having an element manager arranged to control theelement in response to messages from the control layer, the methodcomprising the steps of scanning the element manager to determine thelocation of data files, opening files so found and examining therespective headers thereof for field names, comparing field names with apredetermined list of field names to identify known types of fields andcreating a knowledge file identifying the field locations.

The method may further include the steps of examining each fieldidentified, obtaining numeric information from the fields andincorporating the numeric information in the knowledge file. Preferablythe method includes identifying from the knowledge file entries relatingto physical elements and transmitting to each such physical element atleast one instruction to determine the correct format for the at leastone instruction.

An interface created using the above methods may be incorporated in atranslation table for use by a network control layer.

A communications network may be provided incorporating an interfacecreated using the above method in particular in the network controllayer thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

A communications network of the type having an interface in accordancewith the invention and a method of preparing such an interface will nowbe described by way of example only with reference to the accompanyingdrawing of which:

FIG. 1 is a block schematic diagram showing a typical OSI referencemodel telecommunications network;

FIG. 2 is a block schematic diagram showing the location of elementmanagers within a telecommunications network;

FIG. 3 Shows the location of the interface of the invention with respectto the element manager of FIG. 2;

FIG. 4 shows an alternative implementation to that of FIG. 3;

FIG. 5 shows a first part of a knowledge frame used by the interface ofthe invention;

FIGS. 6 and 7 show respective sub-frames of the knowledge frame of FIG.5; and

FIGS. 8a to 8 d form a flow chart showing the software provided for usein creating the interface of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring first to FIG. 1, the open systems interconnection referencemodel (OSI) proposed by the International Standards Organisation (ISO)to promote network design compatibility is a seven layer design. Eachlayer may include sub-layers but fundamental to the proposal is that theterminal of a lower layer is compatible with (communicates with) theconnection point of the higher layer and vice versa. Lower layersprovide services to higher layers. Accordingly, the OSI digitalcommunications network has a physical layer 1 which is responsible forthe actual transfer of data bits to other physical layer 1 entities atother nodes.

The physical layer 1 activity is carried out on behalf of the data linklayer 2 which arranges the transmission of data packets between nodes inresponse to requirements of the network layer 3 which provides forend-to-end transmission of data packets.

Above the network layer 3, transport layer 4 provides end-to-enddelivery of messages in response to a session layer 5 which sets up andmanages end-to-end communications.

Presentation layer 6 formats and/or compresses data to be transferredwhile application layer 7 provides complete network services such asfile transfer, electronic mail and the like.

The layers 1 to 7 of the OSI model are progressively more intelligentthe higher up they are, but ultimately all rely upon the elements whichmake up the layers below and in particular the parts which effect andcontrol the transfer of digital signals (whether representative of dataor speech, video or graphics) in the physical to network layers 1, 2, 3.

In a practical PSTN, layers 1 to 3 of nodes (A, B, C, D) are embedded inconcentrators, switches, data processors and other physicalcommunication means such as line cards for connection to lines tocustomer premises equipment which dictates the destination of eachcommunication.

Now referring to FIG. 2, the physical layer 1 comprises elements such asline cards for connection to customers, multiplexers and other switches.The network layer 3 includes a network control layer 31 which includeselement manager software 32 to allow communication between the networkcontrol layer 31 and the elements in the physical network. To select apath through the network and to cause an element to behave in apredictable manner the element manager software 32 must cause itsrespective element to respond in a predictable manner to an instructionfrom the network control 31.

However, when a new element, say, a line card is provided in the system,unless it is identical to a removed element it must have a bespokeelement manager 32 provided.

Referring also to FIG. 3, the present invention provides for anadditional software layer, an intelligent interface 33, to be locatedeffectively between the network control layer 31 and each elementmanager 32. Thus, regardless of the type of element manager 32 provided,the network control layer 31 uses a standard generic message for eachtask to be performed by the specified element. The interface 33 musttherefore provide a translation between the control layer message andthe element manager.

While “managers” of “managers” are known, (see for example “IntegratedNetwork Management for Real-Time Operations” by Gary Tjaden and others,IEEE Network Magazine, March 1991, pages 10-15) these comprisetranslation tables manually prepared for each element manager required.The interface 33 of the present invention carries out this task with aminimum of operator intervention once an element is installed in thephysical layer 1 and the corresponding element manager software 32 isprovided in the network layer 3.

The intelligent interface 33 is used by the operator to create aknowledge frame in relation to the specified hardware element which hasbeen inserted. Knowledge frames are described by Marvin Minsky in “ThePsychology of Computer Vision” edited by P H Winston, published in 1975,chapter 6 headed “A Framework for Representing Knowledge”.

In the present case, each type of element which the interface 33 mayencounter could have a specified type of knowledge framework. Thespecific knowledge framework may be selected by the interface as part ofits function during the course of scanning as hereinafter described.Alternatively, the installation operator can specify to the software ofthe intelligent interface 33 the kind of element which has been insertedthus limiting the requirement for software to establish the kind offramework required.

Referring now to FIG. 5, knowledge frames comprise data which fitsparticular situations. Each frame is made up of a hierarchy of nodes andrelations, the higher level nodes being fixed and containing informationwhich is always true in respect of the element represented by the frame.Lower level nodes have additional slots which are filled with data asmore is learnt about the respective element manager.

Consider then a knowledge frame for a transmission element manager. Forthe software in the network control layer to function effectivelyallocation of hardware and the capacity of the hardware are requireditems. Thus, the transmission element manager framework 51 has ahardware data slot 52 and a capacity data slot 53. In hardware 52, forexample, the hardware may be broken down into items for use inmultiplexing 54, control 55, power 56 where in terms of capacity 53traffic handling capability 57 or control information 58 are practicalpropositions.

Referring also to FIG. 6 the hardware frames can be further broken down,for example in multiplexed data the provided element could be line cards61 or multiplex cards 62, where the control comprises, for example,processing power 63, data storage 64 and the power element 56 hasspecifically controller power supply data supply 65 and environmentalinformation 66.

Considering also FIG. 7, the possibility of using sub-frames rather thanfixed data must be considered. Thus, for example the traffic element 57of the capacity knowledge frame 53 may refer out to a sub-frame, forexample, for asynchronous data such as an ATM network (asynchronoustransfer mode) or for synchronous systems such as a time divisionmultiplexed information. Thus, a sub-frame 71 for asynchronous data maydefine cell rate 73 and cell size 74 whilst a sub-frame for synchronousdata 72 will refer to the number of streams 75, 76 and frame format 77which the system is adapted to handle. For completeness it is noted thatfurther frame data for control 58 includes channel associatedinformation data 78 and non-channel specific data 79, for example, tocontrol remote hardware.

Referring additionally to FIGS. 8a-d, the manner in which the knowledgeframes of FIGS. 5 to 7 are filled by the intelligent interface 33 willnow be described. The stages through which the intelligent interfaceproceeds may be defined as “look around”, “try and see”, “followinstructions” and “structured questioning”. Each of these stages willnow be considered in turn.

Referring to FIG. 8a, on installation of an element and its respectivemanager, the operator starts the intelligent interface software at 81and inputs the system type at 82. The interface establishes a link tothe element manager at 83 and scans the element manager at 85 looking atlists, database records etc to search for data on commands used by theauthors of the element manager. This is shown schematically as a searchfor directory structure 85 and, assuming that at least one database isfound, at 86 the located file is opened at 87 and the header of the fileis examined for the database structure. Also from the database structureand header the interface isolates field names within the database at 88and compares these with known field names in its own dictionary at 89.If a known field type is located then that field type and its locationis stored in the knowledge frame at 91 and further investigation of thedatabase continues in FIG. 8b. However, if at 89 an apparent field namedoes not coincide with a known field name from the internal dictionary,then a query is stored for subsequent output to the man machineinterface at 92 and further fields within the same database are checked.

Assuming that one or more correct field names are isolated and theknowledge frame updated with the location of those fields at 91. Then,turning now to FIG. 8b, the look around stage continues with theinterface causing the database to open at 94 to examine fields forentries. Each entry located at 95 is compared with an appropriatesub-dictionary for valid field entries to determine whether a matchoccurs 96. Again if there is no match a query is raised for the manmachine interface at 98 and further fields are examined 99.

Again if at 97 a match is determined between a current field entry andthe sub-dictionary then the knowledge frame is updated with the relevantinformation at 100. Using the numeric limits “highest” “lowest” attainedfrom the field entries the knowledge frame is updated with the terminalrange noted at 102. If there are further fields to examine within thedatabase then the procedure continues until all of the fields of anidentified database have been checked using the procedure of steps 94 to102. Assuming that all of the fields of a particular database have beenchecked then the procedure recommences at step 84 of FIG. 8a for anyother databases found.

Once all of the databases apparently present in the element manager havebeen identified and field entries checked then the software interfaceproceeds to the next stage at FIG. 8c.

In the try and see stage, the interface 33 identifies from the knowledgegathered in the knowledge frame of FIG. 5 and FIG. 6 the entries whichdefine hardware 105, for example, a line card. From the dictionary,having identified the hardware, certain parameters such as on/off orother recognisable physical actions related to the hardware areidentified at 106. Using commands that the element manager might expectfrom a network control sequence, for example a standard enable message107, the interface 33 forwards a signal to try and effect one of theseactions. The hardware will respond in some way, either with anacknowledge message indicating that the function has been carried out,with another message indicating a failure, for example message notunderstood, or with a message perhaps indicating that the parameters areout of range.

If the hardware response indicates that the message has been successfulthen the message format is stored at 111 and the same function iscarried out for other hardware entries held in the knowledge frame inrespect of the particular element manager.

Should no response or a fail response be received from the hardware,then a further different format will be tried at 110 until such time asa success is received.

Having completed steps 105 to 111 for each piece of identified hardware,the interface 33 checks for further operational parameters within thedata entries at 113 and repeats steps 105 to 12 in respect of thoseparameters. At step 114, the steps of 105 to 112 may be repeated forparameters which are stored in the dictionary area of the interface 33rather than being stored in the data entries of the element manager.

Having ascertained the format for commands using try and see theinterface 33 updates the knowledge frame in respect of the particularelement manager at 115 and proceeds to a follow instructions stage. Thisstage shown in FIG. 8d comprises searching the element manager databasefor a “new command” file. If such a file is located, then each of thesecommands is tried in turn and the knowledge frame updated accordingly.Thus, if the element manager author indicates through a standardlanguage such as ASN1 that additional functionality has been provided inthe element, then testing of the functionality and updating of theknowledge frame occurs at steps 116 to 119.

Then, in the structured questioning section, the interface opens its ownquestions file which contains specific pre-specified commands or queriesto which the author of the element manager software will have beenexpected to provide standard answers. The answers to these questionswill provide further information to enable updating of the knowledgeframe at step 121 to 123.

Finally, at step 124, the interface 33 checks for any absence of datawithin the knowledge frame or for any conflict between data heldtherein. Any inconsistency may be passed to the man machine interface atstep 125 along with other queries which have been raised in previousstages of the installation.

Operator responses to queries on the man-machine interface complete thetask of creating an appropriate translation between the network controllayer message structure and the element manager structure.

Whilst the interface software is shown as being in permanentcommunication between the network control layer 31 and the elementmanager 32 (in FIG. 3) it will be appreciated that effectively theintelligent interface 33 automatically creates a translation tablebetween messages output as standard by the network control system of thePSTN operator and the element manager software provided by themanufacturer.

Using the various responses from the element manager, such as “I do notunderstand” where a message does not make sense or “I cannot do that”responses where an acceptable message has been received but theappropriate equipment is not present a translation table can be built.In most cases, as shown in FIG. 4, the interface 33 may simply create atranslation table 35 which sits between the network control layer 31 andthe element manager 32 to provide the functionality required.

What is claimed is:
 1. A method of constructing an interface between acontrol layer and a controlled element of the kind having an elementmanager arranged to control the element in response to messages from thecontrol layer, the method comprising the steps of: scanning the elementmanager to determine the location of data files, opening files so foundand examining the respective headers thereof for field names, comparingsaid field names with a predetermined list of field names to identifyknown types of fields, creating a knowledge file identifying the fieldlocations, and creating said interface between a control layer and acontrolled element using the knowledge file.
 2. The method of claim 1further including the steps of: examining each field identified,obtaining numeric information from the fields, and incorporating thenumeric information in the knowledge file.
 3. An interface created bythe method as in claim 1 and incorporated in a translation table used bythe network controller.
 4. A telecommunications network comprising: aphysical communications layer and a network control layer, the physicalcommunications layer comprising: a multiplicity of elements, eachelement having a respective element manager, the respective elementmanagers being arranged to control respective elements in response tomessages from the network control layer, and the control layer includingan interface created by the method as in claim
 1. 5. Atelecommunications network comprising: a physical communications layerand a network control layer, the physical communications layercomprising: a multiplicity of elements, each element having a respectiveelement manager, the respective element managers being arranged tocontrol respective elements in response to messages from the networkcontrol layer, and the control layer including an interface as in claim3.
 6. A method of constructing an interface between a control layer anda controlled element of the kind having an element manager arranged tocontrol the element in response to messages from the control layer, themethod comprising the steps of: scanning the element manager todetermine the location of data files; opening files so found andexamining the respective headers thereof for field names; comparingfield names with a predetermined list of field names of identify knowntypes of field; creating a knowledge file identifying the fieldlocations; examining each field identified; obtaining numericinformation from the fields and incorporating the numeric information inthe knowledge file; identifying from the knowledge file entries relatingto physical elements; and transmitting to each such physical element atleast one instruction to determine the correct format for the at leastone instruction.
 7. A method of constructing an interface between acontrol layer and a controlled element of the kind having an elementmanager arranged to control the element in response to messages from thecontrol layer, the method comprising the steps of: scanning the elementmanager to determine the location of data files, opening files so foundand examining the respective headers thereof for field names, comparingsaid field names with a predetermined list of field names to identifyknown types of fields, creating a knowledge file identifying the fieldlocations, identifying, from the knowledge file, entries relating tophysical elements, and transmitting to each such physical element atleast one instruction to determine the correct format for the at leastone instruction.
 8. A method of constructing an interface between acontrol layer and a controlled physical element each physical elementhaving a respective element manager arranged to control the element inresponse to messages from the control layer, the method comprising thesteps of: scanning the element manager to determine the location of datafiles, opening files so found and examining the respective headersthereof for field names, comparing said field names with a predeterminedlist of field names to identify known types of fields and creating aknowledge file identifying the field locations, examining eachidentified field and obtaining information from the fields whichinformation is added to said knowledge file, identifying, from theknowledge file, entries relating to said physical elements, andtransmitting to each such physical element at least one instruction todetermine the correct formal for the at least one instruction.
 9. Themethod of claim 8 further including: transmitting to each said physicalelement one instruction in a first format and monitoring the responsefrom said physical element, for each valid response received from aphysical element adding format information in the knowledge file and,for each invalid response, formatting said instruction in a differentmanner and repeating transmission to the physical element.
 10. Aninterface between a network controller and a control element in atelecommunications network, said interface being created using themethod of claim
 8. 11. A telecommunications network comprising: aphysical communications layer and a network control layer, the physicalcommunications layer comprising a multiplicity of physical elements eachhaving a respective element manager, the respective element managersbeing arranged to control respective physical elements in response tomessages from the network control layer, the control layer including atleast one interface created from a knowledge file derived from arespective element manager by determining the location of data files inthe element manager, opening the files and identifying field names,comparing field names with a predetermined list of field names toidentify known types of field, obtaining information from the identifiedfields and adding such information to the knowledge file, andtransmitting at least one instruction to a respective physical elementto determine the correct format for said physical element.